Dispositions, Assets Held for Sale and Discontinued Operations (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013		Sep. 30, 2012
Real property dispositions:
Total dispositions			$ 340,495,000		$ 256,331,000
Gain (loss) on sales of properties, net	4,707,000	12,827,000	57,202,000		46,046,000
Noncash disposition activity			(12,204,000)	[1]	0
Proceeds from sales of real property			385,493,000		302,377,000
Revenues:
Rental income	810,000	20,747,000	5,972,000		70,166,000
Expenses:
Interest expense	12,000	4,328,000	1,535,000		15,504,000
Property operating expenses	68,000	281,000	346,000		1,469,000
Provision for depreciation	313,000	5,014,000	1,879,000		19,899,000
Expenses	393,000	9,623,000	3,760,000		36,872,000
Income (loss) from discontinued operations, net	417,000	11,124,000	2,212,000		33,294,000
Seniors Housing Facilities Triple Net [Member]
Real property dispositions:
Total dispositions			138,650,000		149,984,000
Medical facilities [Member]
Real property dispositions:
Total dispositions			$ 201,845,000		$ 106,347,000

[1] (1) Represents non-cash consideration surrendered in an asset swap transaction. Please see Note 3 for additional information.